Implications of dredging induced changes in sediment particle size composition for the structure and function of marine benthic macrofaunal communities

► We examine benthic community sensitivity to changes in sediment composition. ► Sensitivity increases as the proportion of gravel increases. ► Sensitivity increases as the level of natural physical disturbance decreases. ► Benefit to locating aggregate extraction sites in areas of high disturbance. ► Minimise impacts locally by preserving gravel content of surface sediments. A meta-analysis approach was used to assess the effect of dredging induced changes in sediment composition, under different conditions of natural physical disturbance, for the structure and function of marine benthic macrofaunal communities. Results showed the sensitivity of macrofaunal communities increased as both the proportion of gravel increased and the level of natural physical disturbance decreased. These findings may be explained by the close association of certain taxa with the gravel fraction, and the influence of natural physical disturbance which, as it increases, tends to restrict the colonisation by these species. We conclude that maintaining the gravel content of surface sediments after dredging and, where practicable, locating extraction sites in areas of higher natural disturbance will minimise the potential for long-term negative impacts on the macrofauna.